I've always strongly felt that you can make a "Buffalo buffalo...." sentence with any number of buffalos, and without resorting to the city of Buffalo at all (which I think is cheating).

Without resorting to the city of Buffalo, it becomes much more obvious that the sentence can go on for ever. At each iteration you simply take the object of the previous sentence and make it the subject of the next sentence, and say that those buffalo also bully.

So, first we substitute the word "cows" for the noun "buffalo" and the word "bully" for the verb "buffalo," and then we mark each equivalent noun and noun-phrase (to make the substitutions clear), and we get

Bully! -- the imperative

Cows bully.

Cows bully cows1

[Cows that cows bully]1 bully -- i.e. the cows that were being bullied in #3 themselves also bully

[Cows that cows bully]1 bully cows2

[Cows that [cows that cows bully]1 bully]2 bully -- i.e. the cows that were being bullied in #5 themselves also bully

[Cows that [cows that cows bully]1 bully]2 bully cows3...etc.

The recursive nature becomes much more obvious. Each time a sentence ends with the verb ("bully" i.e. saying that some cows bully), we can ask "well, who do they bully?" And each time we answer that by specifying that they bully cows, we can take those cows (the object of the previous sentence) and say that they themselves (now as the subject) also bully.

Once we realize that (1) any object in a valid sentence, e.g. "cats" in the sentence "dogs bite cats," can be turned into a noun-phrase with an optional "that", e.g. "cats (that) dog bite," and that (2) any animate noun-phrase can be followed by a transitive verb, e.g. "cats dogs bite eat," and finally that (3) transitive verb can take an object, e.g. "cats dogs bite eat mice," we can then prove from those three axioms that we can continue the cycle indefinitely: "mice (that) cats dogs bite eat steal crumbs." And then we don't need to confuse matters with the city of Buffalo.

I'm not sure I'm sold that "Buffalo!" is a grammatical English sentence. "Buffalo" is transitive, and I don't know of a good argument that it has an implicit object. I wouldn't consider "Warn!" or "Have!" grammatical sentences (or "Bully!" for that matter, though it's a perfectly serviceable interjection especially when uttered from underneath circular specs and a walrus mustache).

In fact you can also increase the number of "buffalo"s in the sentence without any additional recursion--which makes the sentence very hard to parse--if you invoke the idea of a "buffalo buffalo"--a buffalo that likes other buffalo, akin to a "people person". So replace the verb "buffalo" with some other verb--"admire", say--and make it about "people people" from the city of Buffalo. Then you get:

[The] Buffalo people people [that] Buffalo people people admire [in turn] admire Buffalo people people.

Putting back "buffalo" for "people", and "buffalo" for "admire", you get a sentence with eleven "buffalo"s and no additional level of recursion.

I think the idea of the original sentence is it's the longest grammatical phrase consisting of one word that specifically doesn't require recursion; allowing recursion makes for a lot more possible sentences but it somehow feels like cheating.

The Lion Eating Poet in the Stone Den ( http://en.m.wikipedia.org/wiki/Lion-Eating_Poet_in_the_Stone_Den ) is a cute example of the same thing in Mandarin but it also feels like cheating as even though it's composed entirely of the phoneme "shi", the fact that Mandarin is tonal means they're actually just vague homophones and not the same word at all, although I guess you could say the same about each "buffalo". That said, it's enough to convince me not to bother learning the language...

Sorry about that...however I think this is relevant because the topic of this BB entry is a series of repeated words accompanied by a WikiP link.

Anyway - although an extreme example...the Buffalo sentence when spoken can make more sense because of how spoken English uses intonation and emphasis as seen by how most people use 'dude' and etcetera. English is unique among most Western languages in this regard.

The Lion Eating Poet in the Stone Den ( http://en.m.wikipedia.org/wiki/Lion-Eating_Poet_in_the_Stone_Den ) is a cute example of the same thing in Mandarin but it also feels like cheating as even though it's composed entirely of the phoneme "shi", the fact that Mandarin is tonal means they're actually just vague homophones and not the same word at all

Though one thing I especially like about that one (at least according to the Wikipedia translation, I understand no Mandarin myself) is that the last line, while still using the same phoneme, is a meta commentary on how difficult the story is to tell.